1. Field of the Invention
This invention involves bistable liquid crystal cells.
2. Description of the Prior Art
The influence and effect of ordered molecules has been used in diverse applications to fabricate devices for switching, modulating and otherwise altering the characteristics of light rays. Liquid crystals, which comprise ordered molecules or groups of molecules in a liquid state, are found to be particularly useful in this regard, since the degree and nature of the ordering can be varied relatively easily to obtain concomitant changes in the transmission properties of the liquid. Differences in transmission, and in the polarizing effect of such liquid crystals, have both been utilized to obtain the now commonly used displays, such as those evidenced by the proliferation of liquid crystal wristwatches. However, it would often be more practical to have a liquid crystal which would have associated with it two stable states, and which can be easily transferred from one stable state to the other, rapidly and with a minimum expenditure of energy. In such a device, little or no energy would be needed to maintain the crystal in either one of the two stable states.
Previous workers have investigated the characteristics of pseudo-stable states in nematic liquid crystals, both twisted and untwisted. However, the absence of a commercial bistable liquid crystal device attests to the failure of the prior art in obtaining a practical and efficient bistable liquid crystal display.